Morphology and function of preserved microvascular arterial grafts: an experimental study in rats

The aim of this study is to examine the morphology and function and small-caliber, arterial grafts after preservation in the University of Wisconsin solution (UW). Rat carotid arteries were stored in UW (n = 10) or in phosphate-buffered saline (PBS) (n = 10) for 1, 3, 7, and 14 days and were examined with light microscopy (LM) and scanning electron microscopy (SEM). Rat aortic preparations were stored in UW or PBS for 1 hour, 24 hours, 72 hours, 7 days, and 14 days and assessed for functional responses (stimulated contraction and endothelium-dependent relaxation). Segments (5 mm) of rat carotid arteries were stored in UW or PBS for 3 days, 7 days, and 14 days and orthotopically implanted as autografts and allografts. No immunosuppressive or anticoagulant agents were used. After 28 days of implantation, the grafts were assessed for patency and excised for LM and SEM. In UW, the endothelial layer remained intact up to 9 days of storage. In PBS, the endothelial layer showed deterioration after 1 day and was completely lost after 3 days. Functional responses were demonstrated to exist for as long as 7 days storage in UW. In PBS, no responses could be evoked after 24 hours storage. Autografts preserved in UW for 3 days (n = 6), 7 days (n = 6), and 14 days (n = 6) showed patency rates of 83.3%, 66.6%, and 66.6%, respectively, whereas patency rates of allografts were 66.6%, 33.3%, and 33.3%, respectively. Autografts stored in PBS for 3 days (n = 6), 7 days (n = 6), and 14 days (n = 6) showed patency rates of 33.3%, 33.3%, and 50%, respectively, whereas patency rates of allografts were 16.7%, 0%, and 33.3%, respectively. The UW preserved autografts showed normal morphology. All other groups showed vessel wall degeneration which in the allograft groups, were accompanied by lymphocellular infiltration. In conclusion, the endothelial layer and vessel wall of arteries are adequately preserved in UW. Functional responses are retained up to 14 days storage in UW, but, are lost after 24 hours storage in PBS. Autograft implantation studies accordingly show good performance of arterial segments preserved in UW, whereas allografts are subject to degradation as a result of rejectio

Morphology and function of dog arterial grafts preserved in UW-solution

Objectives:To assess the function of arterial grafts after prolonged preservation in the University of Wisconsin solution (UW), in vitro and in vivo.Methods:Carotid arteries were harvested from dogs and stored for 1–21 days at 4°C in UW (n = 10) or in PBS (0.9% NaCl, pH 7.4), (PBS) (n = 10). Slices were examined by lightmicroscopy (LM) and scanning electron microscopy (SEM). For viability testing, specimens were connected to an isometric force transducer (2 × n = 9). Contractile and relaxation responses were examined by adding phenylephrine (200μM) and metacholine (200μM), respectively. For in vivo studies (n = 41), 2.5cm carotid artery segments were implanted orthotopically, as autografts and allografts, after 14 days of storage in UW or in PBS. Autologous veins were used as controls. After 28 days or 56 days, arteriography was performed and the grafts were excised for LM and SEM.Results:The arterial endothelial layer remained intact after up to 14 days of storage in UW. In PBS, the endothelium was lost after 3 days. The functional response after 14 days storage in UW was approximately 50% vs. 0% after 14 days in PBS. In the autografts, total patencies (28 days + 56 days) were 100% (8/8) and 63% (5/8) for UW and PBS stored grafts, respectively. In the allografts, the UW and PBS preserved grafts showed total patencies of 86% (12/14) and 83% (5/6), respectively. Microscopically, the allografts showed fibrotic degeneration.Conclusions:Arteries are well preserved in UW up to 14 days of storage. Arterial autografts preserved in UW showed good patency and better integrity of the vessel wall after implantation, than grafts stored in PBS or allografts (without immunosuppressive therapy)

Intravascular ultrasound predictors of outcome after peripheral balloon angioplasty

Objective:This study investigates the potential role of intravascular ultrasound (IVUS) in the outcome in patients undergoing percutaneous transluminal angioplasty (PTA) of the superficial femoral artery.Materials:Angiographic and the qualitative and quantitative IVUS data obtained at the narrowest site derived from 39 patients before and after PTA were analysed.Results:Angiographically the diameter of the remaining stenosis seen after PTA was classified as < 50% in 31 patients (success); in eight patients a failure was encountered. Evaluating at 6 months the functional and anatomic results of the PTA in 31 patients, the intervention was a success in 14 patients (Group I) and a failure in 17 patients (Group II). The remaining eight patients defined as angiographic failure following PTA comprised Group III. Neither qualitative nor quantitative IVUS data obtained before PTA could predict outcome. Conversely, after PTA, the extent of dissection was significantly more severe in Groups II and III than in Group I. Similarly, significant differences were found between Groups I and II for mean free lumen area (13.2 vs. 9.7 mm2, respectively) and mean free lumen diameter (4.1 vs. 3.5 mm, respectively). Quantitative data obtained in Group II were similar to those in Group III.Conclusion:This preliminary study demonstrates that following PTA the extent of dissection, free lumen area and diameter seen with IVUS are predictive factors of patency. Future studies with more patients are mandatory to further highlight the sensitivity of these observations

Function of cryopreserved arterial allografts under immunosuppressive protection with cyclosporine A

Cryopreserved arterial allografts may be used for arterial reconstructive procedures. In this experimental study cryopreserved arteries were used as autografts and as allografts with or without immunosuppression with cyclosporine A. In group A (three dogs, six bilateral grafts) cryopreserved carotid artery autografts were implanted. In groups B and C female mongrel dogs (three dogs and six bilateral grafts in each group) received cryopreserved male carotid artery allografts. Dogs in group C were treated with cyclosporine A (25 mg/kg/day). After 3 months of implantation patency was assessed by angiography. Contractile responses to KCl and phenylephrine (Phe) and the endothelium-dependent relaxation response to methacholine (Met) were examined in segments of the grafts after excision. Medial thickness was assessed semiquantitatively. The grafts were stained for sex chromatin analysis to determine the origin of cells in allografts. Patency: group A, 100% (6 of 6), group B, 66.6% (4 of 6), and group C, 100% (6 of 6). Functional responses: before implantation, after thawing, 2.7 +/- 0.5 mN (KCl), 4.8 +/- 1.0 mN (Phe), and 0.0% +/- 0.0% (Met), group A, 36.9 +/- 10.6 mN (KCl), 31.5 +/- 14.4 mN (Phe), and 59.3% +/- 20.4% (Met), group B, 0 for all agents used, group C, 34.0 +/- 7.5 mN (KCl), 28.8 +/- 7.0 mN (Phe), and 46.2% +/- 3.2% (Met). Morphologic characteristics: the media of grafts in group B showed significant thinning (p < 0.05). Smooth-muscle cells in vessel walls of grafts in group C were of female origin. Arteries showed no function and loss of endothelial integrity after cryopreservation and thawing. After 3 months of implantation cryopreserved arterial autografts and allografts under immunosuppressive treatment with cyclosporine A showed 100% patency and return of functional responses resulting from repopulation of grafts by host cell

Morphology and function of dog arterial grafts preserved in UW-solution

To assess the function of arterial grafts after prolonged preservation in the University of Wisconsin solution (UW), in vitro and in vivo. Carotid arteries were harvested from dogs and stored for 1-21 days at 4 degrees C in UW (n = 10) or in PBS (0.9% NaCl, pH 7.4), (PBS) (n = 10). Slices were examined by lightmicroscopy (LM) and scanning electron microscopy (SEM). For viability testing, specimens were connected to an isometric force transducer (2 x n = 9). Contractile and relaxation responses were examined by adding phenylephrine (200 microM) and metacholine (200 microM), respectively. For in vivo studies (n = 41), 2.5cm carotid artery segments were implanted or orthotopically, as autografts and allografts, after 14 days of storage in UW or in PBS. Autologous veins were used as controls. After 28 days or 56 days, arteriography was performed and the grafts were excised for LM and SEM. The arterial endothelial layer remained intact after up to 14 days of storage in UW. In PBS, the endothelium was lost after 3 days. The functional response after 14 days storage in UW was approximately 50% vs. 0% after 14 days in PBS. In the autografts, total patencies (28 days + 56 days) were 100% (8/8) and 63% (5/8) for UW and PBS stored grafts, respectively. In the allografts, the UW and PBS preserved grafts showed total patencies of 86% (12/14) and 83% (5/6), respectively. Microscopically, the allografts showed fibrotic degeneration. Arteries are well preserved in UW up to 14 days of storage. Arterial autografts preserved in UW showed good patency and better integrity of the vessel wall after implantation, than grafts stored in PBS or allografts (without immunosuppressive therapy

Experimental arterial allografting under low and therapeutic dosages of cyclosporine for immunosuppression

The aim of this study was to investigate performance of preserved arterial allografts under the protection of a high-dose and a low-dose immunosuppressive regimen, with cyclosporine (CsA). Dog carotid arteries were harvested and stored for 14 days at 4 degrees C in University of Wisconsin organ preservation solution. Segments (6 cm) of carotid artery were orthotopically and bilaterally implanted in mongrel dogs (n = 18). CsA was given in two dosage regimens: 25 mg/kg/day (group I, n = 7) and 10 mg/kg/day (group II, n = 7). The control group received no CsA (group III, n=4). After 3 months of implantation, patency was assessed by angiography. The grafts were excised for investigation of vessel wall and endothelial function and morphology. For assessment of function in vitro, slices of arterial segments were connected as ring preparations to an isometric force transducer and immersed in a 5 ml organ bath (37 degrees C) containing Tyrode's solution. The contractile response was examined by adding 40 mM KCl and phenylephrine (100 microM) to the organ bath; endothelium-dependent relaxation was examined by adding methacholine (100 microM). Morphology was assessed semiquantitatively. The functional responses to KCl, phenylephrine (Phe) and methacho- line (Met) after 14 days of storage in UW, were 30.2 +/- 1.2 mN, 26.9 +/- 1.0 and 45 +/- 1.2% (means +/- SEM, n=9), respectively. Patency after three months of implantation for group I was 100% (14/14), for group II 50% (7/14), and for group III 75% (6/8). In vitro functional responses of preserved arteries, after 3 months of implantation in group I were 58.5 +/- 10.6 mN (KCl), 36.5 +/- 5.8 mN (Phe), and 57.4 +/- 9.7% (Met), respectively. Functions in group II were 1.2 +/- 0.1 mN (KCl, 0.0 mN (Phe), and 0.0% (Met). Grafts in group III showed no function. Measurement of medial thickness showed significant thinning (P <0.05) in groups II and III. Patency and function of arterial allografts under a therapeutic dose of CsA were superior to grafts implanted under low-dose CsA or no immunosuppressive treatmen